Method for pulverizing cemented carbides



w th states PATENT QFFHCE METHOD FOR PULVERI ZING CEMENTED CARBIDESFrank F. White, Scotia, N. Y., assignor to General Electric Company, acorporation of New York No Drawing. Application March 30, 1935, SerialNo. 13,931

8 Claims. (Cl. 83-94) The present invention relates to sintered hardtained for a short period of time until the cemetal compositions andmore particularly to cemented carbide pieces are heated throughout atmented carbides and to a, method for treating this temperature afterwhich the pieces are such carbides whereby they may be easily cooled.They then may be crushed easily in any crushed or pulverized. convenientmanner, for example in an ore 5 A cemented carbide is a sinteredcomposition crusher. generally consisting of hard metal carbide par-When the cemented carbide pieces consist subticles cemented together bybinder metal having stantially of tungsten carbide and cobalt, the alower melting point than carbide particles. heating temperature employedis preferably Binder metals commonly employed in cemented above 1600 C.and generally in the neighborhood 10 carbide compositions are metals ofthe iron group of 1700 C. and the heating period ab0ut'30 secorcombinations of metals of the iron group with onds. If a temperaturelower than 1600 C. is other metals such for example as metals of theemployed there may be some difficulty in crush- 6th group ofMendelejeffs Periodic Table of eleing the material while if thetemperature is ma- 5 ments and the quantity of such binder materialterially higher than 1700 c. the cemented caremployed usually variesfrom about 3 to 25% of bide when cooled solidifies into a very hardmass. the weight of the composition although higher The heat treatmentemployed is generally carpercentages of binder material may be employedried out in a carbon receptacle so as to provide a if desired.carbonaceous atmosphere and to thereby pre- Cemented carbides generallyare employed as vent any appreciable reduction in the carbon 20 metalcutting tools or as wire drawing or bendcontent of the heat treatedmaterial. ingjdies. When employed as a metal cutting tool The crushedmaterial provided by the present the cemented carbide is usually in theform of a process may be pressed into desired shapes and small tip whichis copper brazed to a supporting sintered into a hard tough mass in amanner steel shank. Since cemented carbide tools are well known in theart. The invention moreover generally quite brittle there is aconsiderable is not limited to any specific cemented carbide amount ofbreakage of s uch tools. Broken or composition but may be appliedgenerally to any worn tools heretofore have been salvaged by compositionof that character. methods disclosed in the patent to Taylor No. What Iclaim as new and desire to Secure by 1,895,354, January 24, 1933, and inthe patent to Letters Patent of the United States, is: 30 Billings No.31,895,364, January 24, 1933. How- 1. In a method for pulverizing a hardceever, it usually is desirable in salvaging such tools mented carbidecomposition, the steps which that thepieces of the cemented carbide berecomprise heating aid c mented carbide in a duced to a finely dividedor pulverized condition. carbonaceous atmosphere and at a. temperatureThis can be done, as disclosed in the Taylor patsufiiciently high tocause said cemented carbide 35 ent, by crushing the cemented carbide ina morto assume a spongy condition and thereafter tar, the crushing beingfollowed by long ball cooling said spongy material. milling. As a rulethe cost of the crushing and 2-. In amethod for pulverizing a hardcemented ball milling is very high and may exceed the cost carbidecomposition, the steps which comprise 40 of providing an equal weight ofnew ingredients heating said cemented carbide in a carbonaceous 40 inpowdered form. atmosphere and at a temperature sufficiently It is anobject of the present invention to prohigh to cause said cementedcarbide to assume vide a method whereby worn or broken cemented a spongycondition, cooling said spongy material carbide compositions may bepulverized in a r and pulverizing it.

simple, efilcient and inexpensive manner and 3. In a method forpulverizing hard cemented 45 thereafter pressed into any desired shapeand carbide compositions, the steps which comprise sintered into a hardcompact mass. heating said cemented carbide in a carbon tube In carryingout the present invention, pieces at a temperature sufficiently high tocause said of cemented carbide to be salvaged or pulverized cementedcarbide to assume a spongy condition are placed, in any desiredquantity, in a closed and then cooling said spongy material. 50 carbonreceptacle which for example may be in 4. In a method for pulverizingcemented carthe form of a tube about 3" x 6" with walls. bidecompositions, the steps which comprise heat- The tube when loaded isheated to a temperature ing said cemented carbide in acarbon tube at aat which the cemented carbide pieces become temperature sufficientlyhigh to causesaid cespon y or bloated. This temperature is mainmentedcarbide to assume a spongy condition, 55

ing said cemented carbide in a closed carbon recooling said spongymaterial ing it.

5. In a method for pulverizlng cemented carbide compositions, the stepswhich comprise heatand then pulveriztime, cooling the hard metalcomposition from that temperature and pulverizing it. i 7. The methodfor pulverizing a sintered hard metal composition containing about 3 to25% cobalt, the remainder of the composition con- 5 sistlngsubstantially of tungsten carbide which comprises placing the sinteredmaterial in a closed carbon receptacle and heating the receptacle to atemperature in the neighborhood ceptacle at a temperature of about 1600C. to about 1700 C. and cooling the cemented carbide from thattemperature.

6. A method for pulverizing a sintered hard metal composition consistingsubstantially of of 1600" C. to 1700 C. for about 30 seconds, 0001- 10hard metal carbide particles cemented together ing the heated materialand then pulverizing it.

by a binder metal having a lower melting point 8. A method for crushinga cemented carbide, than the carbide particles which comprises heatsaidmethod comprising heating said carbide to lug said sintered compositionin a closed carbon a temperature between about 1600 C. and receptacle ata temperature sufiiciently high to 1700 C., cooling said carbide andthen crushcause said hard metal composition to become ing it.

FRANK F. WHITE.

